A device which, when fed enough data about a person, simulated their personality allowing the user to predict behavior in stated circumstances.

A remarkable idea, one which you see to some extent in some of the Sim products. However, these were simulations for a purpose. Have you ever thought of scheming your way to the top cubicle in your office? These programs are for you.

He entered a larger space full of projection-room gloom with shadowed figures seated facing a holographic focus on his left. McKie identified Jedrik by her profile, slipped into a seat beside her.

McKie recognized the subtle slippage of computer simulation. That was not a flesh-and-blood Broey in the focus.

"Why simulation?"

"He's beginning to do things I didn't anticipate."

Jedrik was reworking the simulation model of Broey which she carried in her head. McKie saw that every seat in the room had an arm keyed to the simulations. The figures at the focus were being adjusted to the combined memories [of those present].

These devices were in common use throughout the civilized universe - or Consentiency, as Herbert puts it in this novel. Employing sound, graphics and basic rules, these simulations were used to help visualize the effect of plans before they were put into action.

In this excerpt, Ceylang (a Wreave), uses the simulator to try to guess Jorj X. McKie's next move.

For almost an hour after the morning meal, Arich observed Ceylang as she worked with the McKie simulation...

Ceylang tried ... a prisoner simulation where five Gowachin tried to confuse McKie by presenting a scenario in which Broey massed his forces at the corridor.

Simulator-McKie asked the prisoners why they lied.

Aritch operated the controls at the observer station. "This might help. This is a record of McKie in recent action on Dosadi."

The simulator presented a view down a covered passage through a building. Artificial light... McKie, two blocky guards in tow, approached the viewers...